At present, flat display devices mainly include liquid crystal display devices and organic light-emitting diode (OLED) display devices. The liquid crystal display device has low power consumption, and gains popularity once it has been emerged.
The liquid crystal display device mainly includes a liquid crystal panel and a backlight module. The backlight module is a component that is arranged at a non-display side of the liquid crystal panel and used for providing a light source for the liquid crystal panel. Liquid crystal molecules are provided in the liquid crystal panel, which can be driven to rotate by an electric field, so that light transmittance of each pixel (color pixel, or black and white pixel) can be adjusted, thereby realizing image display. Since the liquid crystal molecule itself emits no light, the light-emitting performance of the backlight module may directly affect the display performance of the liquid crystal panel.
Light sources of backlight modules can be classified into three categories: a point light source, which mainly adopts an LED (Light-Emitting Diode) lamp as a light-emitting source and has advantages of long service life, low heat generation and the like, but has low brightness; a line light source, which mainly adopts a CCFL (Cold Cathode Fluorescent Lamp) as a light-emitting source and has advantages of high brightness, long service life and the like, but generates a large amount of heat; and a surface light source, which mainly adopts a VFD (Vacuum Fluorescence Display) as a light-emitting source and has advantages of high brightness, good uniformity and the like, but has high power consumption. At present, the backlight module mainly adopts the point light source as a light source, i.e., an LED lamp is used as a light source.
Generally, the backlight module having the point light source includes a light source, a light guide plate, a diffuser, a prismatic lens sheet and the like. The core technique of the backlight module is the optical design of the light guide plate, which can be classified into a flat-plate type and a wedge-shaped type according to its shape, and at present, the wedge-shaped light guide plates are widely adopted. The wedge-shaped light guide plate can achieve conversion from a point light source to a line light source or a surface light source. To achieve the consistencies of grayscale and uniformity, a light guide pattern on a rear surface of the light guide plate is usually arranged in a discontinuity manner, which includes opaque portions that are used for reflecting light to a light-exiting surface of the light guide plate and light-transmitting portions (gaps) arranged between the opaque portions. Part of light may pass through the gaps of the light guide pattern and be scattered to a rear side of the light guide plate (i.e., be away from the light-exiting surface), so that the real utilization of light is low. Moreover, power of the LED lamp has to be increased so as to achieve the expected brightness, so that energy is wasted and cost is high.
Therefore, how to design a backlight module having high light utilization becomes a technical problem to be solved urgently in the prior art.